Recently, interests have been focused on the security technology for controlling access to information as the rapid progress is made in the electronic information and the network information. As one of the security technology, various products for identifying a person by fingerprint verification have been proposed.
For identifying a person, after a fingerprint image is firstly input by a fingerprint sensor, the input fingerprint image is necessary to be verified with registered fingerprint images. As fingerprint verification methods, the characteristic extracting verification method (Minutia(e) matching) and the image matching method (pattern matching method) are conventionally known.
In the characteristic extracting verification method, the structure of the terminations or the bifurcations of the raised portion (ridge) of the fingerprint is extracted as the characteristics (minutia) and the characteristics are compared to verify the fingerprint. The characteristics are extracted after the noise is removed from the input fingerprint image and the image processing such as the contrast processing or the processing of making fine lines is executed. In this method, various rules are included in the program so as not to extract the false characteristics according to the condition of fingers when inputted and the image processing. Therefore, the program includes a complicated algorism and the verification processing time may be varied.
In the image matching method, the similarity of the fingerprint image is directly compared. Because the similarity is checked by shifting the registered fingerprint image and the input fingerprint image, the verification process can be executed relatively fast. However, since the fingerprint image is input and stored, the fingerprint image may be electrically copied. Therefore, it is necessary to settle the security problems.
However, in those conventional methods, either the characteristics are extracted with respect to an image of a whole fingerprint or the whole image is used for verification, so it is required to have a large amount of memory for storing the whole image and a large amount of computing. Therefore, there have been problems in reducing the size of the apparatus and reducing the cost.
To solve the above problems, an object of the present invention is to provide a fingerprint verification apparatus, a fingerprint verification method and a fingerprint verification program for being capable of verifying a fingerprint by extracting a characteristic information from a partial image of a fingerprint without storing a whole image of the fingerprint.